ISHS Acta Horticulturae 779: International Symposium on Growing Media
THE USE OF COMPOSTED MATERIALS IN GROWING MEDIA |
| Author: | W.R. Carlile |
| Keywords: | bark, composted green materials, composted timber wastes, wood fibres |
| Abstract:
Many composted materials have been studied for their potential as constituents of growing media, including bark, wood fibres, manufactured timber by-products and green composted materials, and in global terms their use in media is currently increasing. Composted materials are used widely in some areas of the world: for example composted bark is the principal constituent of growing media in Australia and much is also used in the United States. Over the last decade, increasing use of bark in growing media has occurred in some Western European countries. In the UK, composted by-products of the timber industry, particularly from mass manufacturers of furniture, are used in growing media. During the last ten years, a tremendous upsurge of interest in the use of green composted materials has developed, particularly in Western Europe. Composted or aged bark, with its high air content and good drainage properties is widely used for production of large container grown plants. The species used varies across the world according to local availability, from Pinus radiata bark in Australia, to Pinus sylvestris and Pinus nigra var. maritima in Europe. Composting of bark for two to six months is common practice prior to use as or inclusion in growing media, and advances in composting processes and blending with other materials have alleviated many of the problems formerly associated with bark-based growing media. Research into the use of wood fibres in growing media has been undertaken in France, Germany and the UK, and use of growing media containing composted wood fibres is currently increasing, particularly in the UK. An immense amount of research and development into the use of green composted materials has been undertaken in EU countries. Despite the inherent variability of such media, seasonally and from batch to batch, as well as its high bulk density, intensive promotion and funding leading to improvements in quality and availability of products of a consistent nature has led to the adoption of green composted materials in growing media by some manufacturers of growing media in the UK. Problems of consistency, storage, nitrogen immobilisation and standardisation of composted materials have been addressed through publicly funded research and development studies, as well as in-house and sponsored investigations by manufacturers of growing media. If these improvements in quality and availability are maintained, and lobbyists continue to exert pressures for reduction and/or elimination of peat from growing media, then further increases in the use of composted materials are likely to occur. | |
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